Wireless communication system and base station

ABSTRACT

Admission control wireless resources including abase station which obtains a down wireless resource available rate based on a down QoS requested bandwidth B i  requested by a terminal i during QoS communication and a data rate R i  which the terminal can receive. A down wireless resource usage rate is obtained by dividing a down QoS requested bandwidth B requested by the terminal trying to perform QoS communication by the data rate R which the terminal can receive. An up wireless resource available rate is obtained based on ROT of an up channel and a threshold value T 1  indicating an allowable upper limit of the ROT. The QoS communication is performed on the terminal in which the up and down wireless resource available rates are respectively equal to or more than the up and down wireless resource usage rates.

The present application is a divisional application of application Ser.No. 11/476,058, filed Jun. 28, 2006, the contents of which areincorporated herein with reference.

BACKGROUND OF THE INVENTION

The present invention relates to a wireless communication system and abase station, and particularly to a wireless communication system and abase station in which admission control is performed in a system ofperforming information communication by wireless.

As a Quality of Service (QoS) technique in wireless informationcommunication, there is known a technique in which a wireless resourceis preferentially allocated to a QoS call in order to ensure therequested bandwidth of the QoS call. The wireless resource indicates,for example, a time slot in Time Division Multiple Access (TDMA)communication, total received power allowable to enable demodulation ata receiving end in Code Division Multiple Access (CDMA) communication,or the like.

It has been disclosed that with respect to a terminal requesting QoS, itis confirmed at the time of new call connection or the time of handoffwhether a usable channel element exists, and whether a remainingbandwidth is larger than a bandwidth requested by the terminal, and whenthe channel element exists and the remaining bandwidth is larger thanthe requested bandwidth, the call connection is performed (see, forexample, patent document 1). In the case where the usable channelelement does not exist, or in the case where, although the usablechannel element exists, the remaining bandwidth is smaller than therequested bandwidth of the terminal, the call connection is notperformed. By the processing as stated above, for example, according tothe technique of patent document 1, the QoS can be ensured for thecall-connected QoS requesting terminal.

Patent Document 1: JP-A-2003-264878

SUMMARY OF THE INVENTION

The amount of wireless resources consumed to ensure the requestedbandwidth with the same magnitude is different between a time when thewireless environment is good and a time when the wireless environment ispoor. In general, the worse the wireless environment is, the more thewireless resources are consumed.

FIGS. 9A and 9B show a relation between a bandwidth and a wirelessresource while the TDMA is used as an example. In this example, it isassumed that 10 time slots exist in 1 second, and 1 kbit or 3 kbits canbe selectively stored in 1 time slot by changing a modulation system.The maximum bandwidth of this channel is 30 kbps. In the case where thewireless environment is good, the modulation system is used in which 3kbits are stored in each time slot, while in the case where the wirelessenvironment is poor, the modulation system is used in which 1 kbit isstored in each time slot. Here, as an example, consideration is given toa case where a requested bandwidth of 6 kbps is ensured.

FIG. 9A shows an example of a case where the wireless environment isgood. In the case where the wireless environment is good, 3 kbits can bestored in 1 time slot, and 2 time slots are occupied in order to ensure6 kbits. Accordingly, the wireless resource usage rate becomes 0.2 (thenumber of used slots is 2, the number of all time slots is 10). FIG. 9Bshows an example of a case where the wireless environment is poor. Inthe case where the wireless environment is poor, since only 1 kbit canbe stored in 1 time slot, 6 time slots are occupied in order to ensure 6kbps. Accordingly, the wireless resource usage rate becomes 0.6 (thenumber of used slots is 6, the number of all time slots is 10).

Consideration is given to a case where a bandwidth of 6 kbps is furtherrequired in this state. In both FIGS. 9A and 9B, a bandwidth of 24 kbitis available. However, according to the wireless environment of theterminal requesting the bandwidth, there is a case where the requested 6kbps can not be ensured. For example, in the example of FIG. 9A, 6 kbpscan be ensured in both the foregoing modulation systems, and in FIG. 9B,6 kbps can be ensured in the modulation system of storing 3 kbits in 1time slot. However, the example of FIG. 9B is the example in which thewireless environment is poor, and unless the wireless environment ischanged, the modulation system in which 1 kbit is stored in 1 time slotis used, and 6 time slots are required in order to ensure the bandwidthof 6 kbps. Accordingly, although the bandwidth of 24 kbps exists, thewireless resource is insufficient, and the required 6 kbps can not beensured.

In the technique disclosed in patent document 1, a judgment as towhether or not the QoS can be provided is made based on whether or notthe available bandwidth is larger than the required bandwidth. However,even if call connection is allowed since the available bandwidth islarger than the requested bandwidth, as described above, a case canoccur in which the wireless resource is not actually available, and therequested bandwidth can not be ensured. Accordingly, it is desired tomake a call connection possible/impossible judgment using, as an index,the usage rate of the wireless resource, not the requested bandwidth.

Besides, according to the technique disclosed in patent document 1, withrespect to a QoS-capable terminal in which QoS provision is madepossible at the time of call connection, the QoS is ensured. However,the wireless environment is changed from hour to hour by phasing orshadowing, and a time can occur in which the requested bandwidth can notbe ensured on the time axis. At that time, in order to satisfy therequested bandwidth, the QoS terminal is controlled to use more wirelessresources, and this becomes a large load for the wireless resource. Thatis, the terminal hinders the QoS provision to another QoS-capableterminal. With respect to the terminal in such a state, it is desired toprovide a measure not to hinder the QoS provision to the anotherterminal.

In view of the above, the invention has an object to provide admissioncontrol to perform the new call connection of a terminal and callconnection to a handoff destination in view of wireless resources.Besides, the invention has an object to take measures to prevent aterminal having a high wireless resource usage rate from disturbing QoSto other terminals in a case where a wireless resource usage ratebecomes high.

Besides, the invention has an object to provide admission control inwhich a judgment as to whether or not QoS provision can be provided ismade by using an index of a wireless resource usage rate, and whichprevents that a call-connected QoS requesting terminal can not start QoScommunication because of insufficiency of wireless resources. Besides,the invention has an object to increase QoS calls which can receive QoSprovision. The invention has an object to call-connect a new QoSrequesting terminal.

An index of a wireless resource usage rate is provided. The index ismanaged for each terminal and each channel, and the judgment as towhether or not QoS can be provided is made by using the index.

(1) According to one of the solving means of the invention, the index ofthe wireless resource usage rate is provided, a wireless resourceavailable rate of a channel and a wireless resource usage rate necessaryto ensure a requested bandwidth of a terminal requesting connection arecompared with each other at the time of QoS call connection, and the QoScall connection is performed when the available rate is larger.

(2-1) According to another solving means of the invention, the wirelessresource usage rate of a channel is periodically calculated, and in acase where the wireless resource usage rate of the channel exceeds afirst threshold value, wireless resource usage rates of respectiveQoS-capable terminals are calculated, and among the QoS-capableterminals, a terminal in which the wireless resource usage rate exceedsa second threshold value is changed to best effort.

(2-2) In a case where the wireless resource usage rate of the channelexceeds the first threshold value and another channel exists, theterminal is handed off to the another channel. At that time, a terminalis handed off in which both the wireless resource usage rate of thehandoff source channel after the handoff and the wireless resource usagerate of the handoff destination channel become lower than the firstthreshold value.

More specifically, a wireless communication system includes a basestation, and the base station uses a wireless resource usage rate as anindex and judges whether or not QoS can be provided. Besides, at thetime of new call connection of a terminal or call connection to ahandoff destination, as to whether or not QoS can be provided, the basestation makes a handoff possible/impossible judgment by comparing theremainder of the wireless resource of the channel with a wirelessresource estimated to be occupied by the terminal at the time of QoS.

The base station monitors the wireless resource usage rate of thechannel, and in the case where the wireless resource usage rate exceedsthe first threshold value, the QoS terminal in which the wirelessresource usage rate exceeds the second threshold value is changed tobest effort. Here, the first threshold value is a threshold value whichserves as an opportunity to cause the base station to start a processingof changing the QoS terminal in which the wireless resource usage rateexceeds the second threshold value to the best effort. Besides, thesecond threshold value is a threshold value which becomes a criterion ofjudgment as to whether or not the base station changes the QoS terminalto the best effort, and for example, the QoS terminal in which thewireless resource usage rate exceeds the second threshold value ischanged to the best effort.

In the foregoing wireless communication system, in the case where thewireless resource usage rate still exceeds the first threshold valueafter the foregoing procedure is performed, when another channel existsand when a QoS terminal exists in which wireless resource usage rates ofboth the handoff source channel and the handoff destination channelbecome the first threshold value or less by handing off the QoS terminalto the another channel, the base station hands off the terminal to theanother channel.

According to the first solving means of this invention, there isprovided

a base station in a wireless communication system comprising the basestation to communicate with a terminal by wireless and by time divisionmultiplexing, and a node to perform best effort communication and QoScommunication with the terminal through the base station,

wherein the base station comprises:

a requested bandwidth storage part in which a first requested bandwidthrequested by one or plurality of first terminals during QoScommunication and a second requested bandwidth requested by a secondterminal trying to perform QoS communication are stored for eachterminal;

a data rate reception management part that receives a data amount whichthe first and the second terminal can receive in each time slot from theterminals, which depends on changing the data amount stored in each timeslot according to wireless environment, calculates a first and a seconddata rates which the first and the second terminals can receive byobtaining a time average value of the data amount for each terminal, andstores the data rates for each terminal; and

a control part to control the base station, and

wherein the control part obtains a wireless resource available rate,based on a first requested bandwidth B_(i) which is stored in therequested bandwidth storage part and is requested by the first terminali, and a first data rate R_(i) which the first terminal i can receiveand which is stored in the data rate reception management part, by afollowing expression:

$1 - {\sum\limits_{i}\frac{B_{i}}{R_{i}}}$

the control part obtains a wireless resource usage rate of the secondterminal necessary to ensure the second requested bandwidth B, bydividing the second requested bandwidth B which is stored in therequested bandwidth storage part and is requested by the second terminalby the second data rate R which the second terminal can receive andwhich is stored in the data rate reception management part, and

the control part transmits, with respect to the second terminal in whichthe wireless resource available rate is equal to or more than thewireless resource usage rate, a connection establishment request forQoS, for performing QoS communication between the second terminal andthe node, to the node.

According to the second solving means of this invention, there isprovided

a base station in a wireless communication system comprising the basestation to communicate with a terminal by wireless and by code divisionmultiplexing, and a node to perform best effort communication and QoScommunication with the terminal through the base station,

wherein the base station comprises:

a requested bandwidth storage part in which a requested bandwidth isstored for each terminal;

an S/N management part to store a value of S/N of a pilot channel foreach terminal;

an ROT management part to store a value of ROT (Rise Over Thermal) foreach channel;

where, ROT is defined by a following expression

(I₀+N₀)/N₀

here, I₀ is total of received power from all terminals, N₀ is thermalnoise power,

a threshold value storage part to store a previously determinedthreshold value indicating an allowable upper limit of the ROT; and

a control part to control the base station, and

wherein

the control part obtains a wireless resource available rate, based on avalue T of ROT of a channel stored in the ROT management part and athreshold value T₁ stored in the threshold value storage part, by afollowing expression:

1−T/T₁,

the control part obtains a wireless resource usage rate of the secondterminal, which is necessary to ensure the requested bandwidth stored inthe requested bandwidth storage part and is requested by the secondterminal, by a following expression:

A×P×T/T₁,

where, A is a ratio of total transmission power to transmission power ofa pilot channel when the second terminal transmits data in the requestedbandwidth, and uniquely determined according to the requested bandwidth,P is an S/N value of the pilot channel of the second terminal stored inthe S/N management part, T is ROT of a channel stored in the ROTmanagement part, and T₁ is a previously determined threshold valueindicating an allowable upper limit of ROT, which is stored in thethreshold value storage part, and the control part transmits, withrespect to the second terminal in which the wireless resource availablerate is equal to on more than the wireless resource usage rate, aconnection establishment request for QoS, for performing QoScommunication between the second terminal and the node, to the node.

According to the third solving means of this invention, there isprovided a base station in a wireless communication system comprisingthe base station to communicate with a terminal by wireless, by timedivision multiplexing in a downward direction to the terminal, and bycode division multiplexing in an upward direction from the terminal, anda node to perform best effort communication and QoS communication withthe terminal through the base station,

wherein the base station comprises:

a requested bandwidth storage part in which a first down requestedbandwidth requested by one or plurality of first terminals during QoScommunication, a second down requested bandwidth requested by a secondterminal trying to perform QoS communication, and an up requestedbandwidth are stored for each terminal;

a data rate reception management part that receives a data amount whichthe first and the second terminals can receive in each time slot fromthe terminals, which depends on changing the data amount stored in eachtime slot according to wireless environment, calculates a first and asecond data rates which the first and the second terminals can receiveby obtaining a time average value of the data amount for each terminal,and stores the data rates for each terminal;

an S/N management part to store a value of S/N of a pilot channel foreach terminal;

an ROT management part to store a value of ROT (Rise Over Thermal) foreach up channel;

a threshold value storage part to store a previously determinedthreshold value indicating an allowable upper limit of the ROT; and

a control part to control the base station, and

wherein the control part obtains a down wireless resource availablerate, based on a first down requested bandwidth B_(i) which is stored inthe requested bandwidth storage part and is requested by the firstterminal i, and a first data rate R_(i) which the first terminal i canreceive and which is stored in the data rate reception management part,by a following expression:

$1 - {\sum\limits_{i}\frac{B_{i}}{R_{i}}}$

the control part obtains a down wireless resource usage rate of thesecond terminal necessary to ensure the second requested bandwidth B, bydividing the second down requested bandwidth B which is stored in therequested bandwidth storage part and is requested by the second terminalby the second data rate R which the second terminal can receive andwhich is stored in the data rate reception management part,

the control part obtains an up wireless resource available rate, basedon a value T of ROT of an up channel stored in the ROT management partand a threshold value T₁ stored in the threshold value storage part, bya following expression:

1−T/T₁,

the control part obtains an up wireless resource usage rate of thesecond terminal, which is necessary to ensure the up requested bandwidthstored in the requested bandwidth storage part and is requested by thesecond terminal, by a following expression:

A×P×T/T₁,

where, A is a ratio of total transmission power to transmission power ofa pilot channel when the second terminal transmits data in the uprequested bandwidth, and uniquely determined according to the uprequested bandwidth, P is an S/N value of the pilot channel of thesecond terminal stored in the S/N management part, T is ROT of an upchannel stored in the ROT management part, and T₁ is a previouslydetermined threshold value indicating an allowable upper limit of ROT,which is stored in the threshold value storage part, and the controlpart transmits, with respect to the second terminal in which the downwireless resource available rate is equal to or more than the wirelessresource usage rate, and in which the up wireless resource availablerate is equal to or more than the up wireless resource usage rate, aconnection establishment request for QoS, for performing QoScommunication between the second terminal and the node, to the node.

According to the fourth solving means of this invention, there isprovided a base station in a wireless communication system comprisingthe base station having a first and a second channels and communicatingwith a terminal by wireless and by time division multiplexing, and anode to perform best effort communication and QoS communication with theterminal, wherein

the base station obtains a first wireless resource usage rate in thefirst channel, based on a first requested bandwidth B_(i) requested byone or plurality of first terminals i during QoS communication throughthe first channel and a first data rate R_(i) which the first terminal ican receive and which depends on changing a data amount stored in eachtime slot according to wireless environment, by a following expression:

$\sum\limits_{i}\frac{B_{i}}{R_{i}}$

the base station obtains a second wireless resource usage rate of thesecond terminal, which is necessary to ensure a requested bandwidth B,by dividing the second requested bandwidth B requested by an arbitrarysecond terminal during QoS communication through the first channel by asecond data rate R which the second terminal can receive,

the base station obtains a predicted value of a wireless resource usagerate in the first channel after the second terminal hands off to thesecond channel by subtracting the second wireless resource usage rate ofthe second terminal from the first wireless resource usage rate in thefirst channel,

the base station obtains a third wireless resource usage rate in thesecond channel, based on a third requested bandwidth B_(k) requested byone or plurality of third terminals k during QoS communication throughthe second channel and a third data rate R_(k) which the third terminalk can receive, which depends on changing a data amount stored in eachtime slot according to wireless environment, by a following expression:

$\sum\limits_{k}\frac{B_{k}}{R_{k}}$

the base station obtains a fourth wireless resource usage rate of thesecond terminal after the second terminal hands off to the secondchannel, by dividing the second requested bandwidth B requested by thesecond terminal by an average R_(AVE) of the data rate which eachterminal communicating through the second channel can receive,

the base station obtains a predicted value of a wireless resource usagerate in the second channel after the second terminal hands off to thesecond channel by adding the fourth wireless resource usage rate in thesecond terminal to the third wireless resource usage rate in the secondchannel, and

the base station hands off the second terminal from the first channel tothe second channel in a case where both the obtained predicted value ofthe wireless resource usage rate in the first channel and the predictedvalue of the wireless resource usage rate in the second channelrespectively become equal to or less than previously determinedthreshold values. According to the fifth solving means of thisinvention, there is provided

a base station in a wireless communication system comprising the basestation having a first and a second channels and communicating with aterminal by wireless and by code division multiplexing, and a node toperform best effort communication and QoS communication with theterminal, wherein

the base station obtains a first wireless resource usage rate in thefirst channel, by dividing ROT (Rise Over Thermal) T_(a) of the firstchannel by a previously determined first ROT threshold value T₁indicating an allowable upper limit of the ROT,

the base station obtains a second wireless resource usage rate of thesecond terminal, which is necessary to ensure a requested bandwidthrequested by an arbitrary second terminal during QoS communicationthrough the first channel, by a following expression:

A×P×T_(a) /T ₁,

where, A is a ratio of total transmission power to transmission power ofa pilot channel when the second terminal transmits data in the requestedbandwidth, and uniquely determined according to the requested bandwidth,P is S/N of the pilot channel of the second terminal, T_(a) is ROT ofthe first channel, and T₁ is a previously determined first ROT thresholdvalue indicating an allowable upper limit of ROT,

the base station obtains a predicted value of a wireless resource usagerate in the first channel after the second terminal hands off to thesecond channel by subtracting the second wireless resource usage rate inthe second terminal from the first wireless resource usage rate in thefirst channel,

the base station obtains a third wireless resource usage rate in thesecond channel, by dividing ROT T_(b) of the second channel by apreviously determined second threshold value T₂ indicating an allowableupper limit of the ROT,

the base station obtains a fourth wireless resource usage rate of thesecond terminal after the second terminal hands off to the secondchannel by a following expression:

A×P_(AVE)×T_(b)/T₂,

where, A is a ratio of total transmission power to transmission power ofthe pilot channel when the second terminal transmits data in therequested bandwidth, and uniquely determined according to the requestedbandwidth, P_(AVE) is an average of S/N of the pilot channel of allterminals communicating through the second channel, T_(b) is ROT of thesecond channel, and T₂ is a previously determined second ROT thresholdvalue indicating an allowable upper limit of the ROT,

the base station obtains a predicted value of a wireless resource usagerate in the second channel after the second terminal hands off to thesecond channel by adding the fourth wireless resource usage rate in thesecond terminal to the third wireless resource usage rate in the secondchannel, and

the base station hands off the second terminal from the first channel tothe second channel in a case where both the obtained predicted value ofthe wireless resource usage rate in the first channel and the predictedvalue of the wireless resource usage rate in the second channelrespectively become equal to or less than previously determinedthreshold values.

According to the sixth solving means of this invention, there isprovided a wireless communication system comprising:

a base station to communicate with a terminal by wireless and by timedivision multiplexing; and

a node that has a QoS information table in which a requested bandwidthrequested by the terminal is previously stored correspondingly to anidentifier of the terminal and performs best effort communication andQoS communication with the terminal through the base station,

wherein the base station comprises:

a requested bandwidth storage part in which a first requested bandwidthrequested by one or plurality of first terminals during QoScommunication and a second requested bandwidth requested by a secondterminal trying to perform QoS communication are stored for eachterminal;

a data rate reception management part that receives a data amount whichthe first and the second terminals can receive in each time slot fromthe terminals, which depends on changing the data amount stored in eachtime slot according to wireless environment, calculates a first and asecond data rates which the first and the second terminals can receiveby obtaining a time average value of the data amount for each terminal,and stores the data rates for each terminal; and

a control part to control the base station,

wherein the node receives a connection establishment request for besteffort, which includes an identifier of the second terminal trying toperform QoS communication, from the base station, and previouslyestablishes connection for best effort between the second terminal andthe node, and

the node refers to the QoS information table and transmits a secondrequested bandwidth corresponding to the identifier of the secondterminal included in the establishment request to the base station,

the control part stores the second requested bandwidth received from thenode into the requested bandwidth storage part,

the control part obtains a wireless resource available rate, based on afirst requested bandwidth B_(i) which is stored in the requestedbandwidth storage part and is requested by the first terminal i and afirst data rate R_(i) which the first terminal i can receive and whichis stored in the data rate reception management part, by a followingexpression:

$1 - {\sum\limits_{i}\frac{B_{i}}{R_{i}}}$

the control part obtains a wireless resource usage rate of the secondterminal, which is necessary to ensure the second requested bandwidth B,by dividing the second requested bandwidth B which is stored in therequested bandwidth storage part and is requested by the second terminalby the second data rate R which the second terminal can receive andwhich is stored in the data rate reception management part, and

the control part transmits, with respect to the second terminal in whichthe wireless resource available rate is equal to or more than thewireless resource usage rate, a connection establishment request forQoS, for performing QoS communication between the second terminal andthe node, to the node.

According to the seventh solving means of this invention, there isprovided a wireless communication system comprising:

a base station to communicate with a terminal by wireless and by codedivision multiplexing; and

a node that has a QoS information table in which a requested bandwidthrequested by the terminal is previously stored correspondingly to anidentifier of the terminal and performs best effort communication andQoS communication with the terminal through the base station,

wherein the base station comprises:

a requested bandwidth storage part in which a requested bandwidth isstored for each terminal;

an S/N management part to store a value of S/N of a pilot channel foreach terminal;

an ROT management part to store a value of ROT (Rise Over Thermal) foreach channel;

a threshold value storage part to store a previously determinedthreshold value indicating an allowable upper limit of the ROT; and

a control part to control the base station,

wherein the node receives a connection establishment request for besteffort, which includes an identifier of a second terminal trying toperform QoS communication, from the base station, and previouslyestablishes connection for best effort between the second terminal andthe node, and

the node refers to the QoS information table and transmits a requestedbandwidth corresponding to the identifier of the second terminalincluded in the establishment request to the base station,

the control part stores the second requested bandwidth received from thenode into the requested bandwidth storage part,

the control part obtains a wireless resource available rate, based on avalue T of ROT of a channel stored in the ROT management part and athreshold value T₁ stored in the threshold value storage part, by afollowing expression:

1−T/T₁,

the control part obtains a wireless resource usage rate of the secondterminal, which is necessary to ensure a requested bandwidth stored inthe requested bandwidth storage part and is requested by the secondterminal, by a following expression:

A×P×T/T₁,

where, A is a ratio of total transmission power to transmission power ofa pilot channel when the second terminal transmits data in the requestedbandwidth, and uniquely determined according to the requested bandwidth,P is an S/N value of the pilot channel of the second terminal stored inthe S/N management part, T is ROT of a channel stored in the ROTmanagement part, and T₁ is a previously determined threshold valueindicating an allowable upper limit of ROT, which is stored in thethreshold value storage part, and

the control part transmits, with respect to the second terminal in whichthe wireless resource available rate is equal to or more than thewireless resource usage rate, a connection establishment request forQoS, for performing QoS communication between the second terminal andthe node, to the node.

According to the invention, it is possible to provide the admissioncontrol to perform the new call connection of a terminal and callconnection to a handoff destination in view of the wireless resources.Besides, according to the invention, in the case where the wirelessresource usage rate becomes high, measures can be taken to prevent aterminal having a high wireless resource usage rate from disturbing theQoS of another terminal.

Besides, according to the invention, it is possible to provide theadmission control in which the judgment as to whether or not the QoS canbe provided is made by using the index of the wireless resource usagerate, and which prevents that a call-connected QoS requesting terminalcan not start the QoS communication because of insufficiency of wirelessresources. Besides, according to the invention, QoS calls which canreceive the QoS provision can be increased. According to the invention,it becomes possible to call-connect a new QoS requesting terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system structural view of a wireless informationcommunication system to which the invention is applied.

FIG. 2 is a functional block diagram of a base station in the wirelessinformation communication system to which the invention is applied.

FIGS. 3A and 3B show data formats (1) of respective blocks of the basestation.

FIGS. 4A and 4B show data formats (2) of respective blocks of the basestation.

FIG. 5 shows an example of a QoS information table owned by PDSN.

FIG. 6 is a sequence view of connection establishment at a time of newcall connection of a terminal or at a time of call connection to ahandoff destination in the wireless information communication system towhich the invention is applied.

FIG. 7 is a flowchart relating to one of solving means of the invention.

FIG. 8 is a flowchart relating to another solving means of theinvention.

FIGS. 9A and 9B are views showing a relation between a bandwidth and awireless resource while TDMA is used as an example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 1. FirstEmbodiment Hardware Structure

A description will be made while as a wireless communication system, a1×EV-DO (1× Evolution Data Only) system is used as an example.

FIG. 1 is a view showing an example of a system structure of the 1×EV-DOsystem. The 1×EV-DO system includes, for example, terminals 110, basestations 120, an IP-SW (IP Switch) 130, and a PDSN (Packet Data ServingNode) 140. The PDSN 140 is connected to the Internet 150. Besides, thePDSN includes a QoS information table 141.

Wireless communication is provided between the base station 120 and theterminal 110, and is indicated by a broken line in the figure. On theother hand, a solid line in the figure indicates cable communication. Inthis example, transmission (down) from the base station 120 to theterminal 110 is TDMA communication, and transmission (up) from theterminal 110 to the base station 120 is CDMA communication. Pluralchannels exist in each of the down transmission and the up transmission.

FIG. 2 is a functional block diagram of the base station 120 in thisembodiment. Besides, FIGS. 3A and 3B and FIGS. 4A and 4B show dataformats of respective blocks of the base station 120.

The base station 120 includes a requested bandwidth storage part 510, aROT (Rise Over Thermal) threshold value storage part 520, a control part530, a handoff instruction part 540, a receivable data ratereception-management part 550, an S/N reception-management part 560, aROT reception-management part 570, and a channel management part 580.

In the requested bandwidth storage part 510, a down QoS requestedbandwidth of a terminal i to which a call is connected, an up QoSrequested bandwidth, and a value of a ratio A_(i) of the totaltransmission power to transmission power of a pilot channel when theterminal i transmits data in the up QoS requested bandwidth are storedfor each of the terminals 110. For example, the down and up QoSrequested bandwidths of each terminal 110 to perform the QoScommunication are acquired from the QoS information table 141 of thePDSN 140 and are stored in the requested bandwidth storage part 510.FIG. 3A shows an example of a table structure. For example, with respectto each channel managed by the base station 120, each data is stored(the figure shows an example of a channel 1).

A previously set ROT threshold value is stored in the ROT thresholdvalue storage part 520. The ROT threshold value may be stored for eachchannel. The handoff instruction part 540 transmits, to the terminal110, an instruction to perform handoff to a specified different channel.The receivable data rate reception-management part 550 receives, foreach terminal 110, a data rate (data amount per 1 time slot) receivablein 1 time slot of the terminal 110 from the terminal 110. Besides, thereceivable data rate reception-management part 550 calculates a timeaverage value R_(i) for each terminal i, obtains the data rate which theterminal 110 can receive, and manages and stores it. The time averagevalue R_(i) can be made, for example, a data rate (bps) per 1 second.For example, it is assumed that in a channel having 10 slots per 1second (that is, 1 slot has 0.1 second), the data rate which theterminal 110 can receive in 1 time slot is 3 kbits. The time averagevalue R_(i) in this case is 3/0.1=30 kbps. FIG. 3B shows an example of atable structure. For example, with respect to each channel managed bythe base station 120, each data is stored (the figure shows an exampleof the channel 1).

The S/N reception-management part 560 receives the S/N of a pilotchannel for each terminal 110, and stores, for example, the S/Ncorrespondingly to an identifier of the terminal 110. It is receivedfrom, for example, a suitable block (not shown) in the base station 120to receive the pilot channel. FIG. 4A shows an example of a tablestructure. For example, with respect to each channel managed by the basestation 120, each data is stored (the figure shows an example of thechannel 1).

The ROT reception-management part 570 receives the ROT for each upchannel, and stores the ROT correspondingly to, for example, anidentifier of a channel. For example, it is received from a suitableblock (not shown) in the base station 120 to obtain the ROT. FIG. 4Bshows an example of a table structure. The channel management part 580manages channels provided by the base station 120.

FIG. 5 shows the QoS information table 141 stored in the PDSN 140. ThePDSN 140 includes the QoS information table 141 in which QoS informationis previously stored correspondingly to a terminal registration number.For example, it is stored in a suitable memory or the like. The QoSinformation includes, for example, a down QoS requested bandwidth and anup QoS requested bandwidth. Incidentally, a suitable identifier toidentify the terminal 110 can be used as the terminal registrationnumber. Besides, with respect to the terminal 110 in which the QoS isnot performed, no data may be stored, or previously determined specificdata, such as zero or null, may be stored.

(Wireless Resource Usage Rate)

Here, the wireless resource usage rate in this embodiment will bedefined.

Since the down transmission is the TDMA communication, the wirelessresource usage rate is a time slot allocation rate. For example, as inFIG. 9A, when 2 time slots are used in a channel having 10 time slotsper 1 second, the wireless resource usage rate is 0.2.

The terminal 110 transmits a data rate which can be received in eachtime slot to the base station 120, and in the base station 120, a valueR_(i) obtained by time-averaging that is managed in the receivable datarate reception-management part 550. The slot allocation rate of the ithterminal 110 in the channel becomes

B_(i)/R_(i)  (1)

by using the down QoS requested bandwidth B_(i) of the ith terminal andthe average R_(i) of the data rate which the terminal 110 can receive.

In the example of FIG. 9A, the terminal 110 has the QoS requestedbandwidth B_(i)=6 kbps. Since 3 kbits can be stored in 1 time slot, andthere are 10 time slots in 1 second, the average R_(i) of the data ratewhich the terminal 110 can receive is 30 kbps. Accordingly, from theforegoing expression (1), the slot allocation rate (wireless resourceusage rate) of the terminal 110 becomes 6/30=0.2. Besides, in theexample of FIG. 9B, the terminal 110 has the QoS requested bandwidthB_(i)=6 kbps. Besides, since 1 kbit can be stored in 1 time slot, andthere are 10 time slots in 1 second, the average R_(i) of the data ratewhich the terminal 110 can receive is 10 kbps. Accordingly, from theforegoing expression (1), the slot allocation rate (wireless resourceusage rate) of the terminal 110 is 6/10=0.6.

Besides, the slot allocation rate of all channels becomes as follows.

$\begin{matrix}{\sum\limits_{i}\frac{B_{i}}{R_{i}}} & (2)\end{matrix}$

On the other hand, since the up transmission is the CDMA communication,when ROT in the base station 120 becomes large, demodulation of a signalfrom each terminal 110 becomes difficult. Accordingly, the ROT is usedas the index of the wireless resource usage rate of a channel. When thevalue of the ROT is made T, and the allowable upper limit of the ROT ismade a ROT threshold value T₁, the wireless resource usage rate of thechannel becomes as follows.

T/T₁.  (3)

Incidentally, as the value T of the ROT, the value received and storedby the ROT reception-management part 570 can be used. Besides, as theROT threshold value T₁, the value stored in the ROT threshold valuestorage part 520 can be used.

The wireless resource usage rate of the ith terminal 110 in the channelis the extent of contribution of the terminal 110 in the ROT of all thechannels, and becomes as follows.

$\begin{matrix}{A_{i} \times P_{i} \times \frac{T}{T_{1}}} & (4)\end{matrix}$

Here, Ai denotes the ratio of the total transmission power to thetransmission power of the pilot channel when the terminal i transmitsdata in the up QoS requested bandwidth, and has a unique correspondencerelation to the up QoS requested bandwidth. Pi denotes the S/N of thepilot channel of the terminal i which the base station 120 receives. Aiis uniquely obtained based on the QoS requested bandwidth and is storedin the requested bandwidth storage part 510. Pi is received and storedin the S/N reception-management part 560.

(Operation)

First, in this embodiment, a description will be given to a QoSprovision possible/impossible determination processing at the time ofnew call connection of the terminal 110 or at the time of callconnection to a handoff destination.

FIG. 6 is a sequence view of connection establishment at the time of newcall connection or at the time of call connection to a handoffdestination. First, a negotiation for communication start is performedbetween the terminal 110 and the base station 120 (processing 201). Forexample, the terminal 110 transmits a terminal registration number tothe base station 120, and the base station 120 assigns an identificationID to the terminal 110. The terminal registration number is previouslystored in the terminal 110.

When the negotiation is completed, the base station 120 transmits aconnection establishment request for best effort to the PDSN 140(processing 202). The connection establishment request for best effortincludes the terminal registration number received from the terminal110. When receiving the connection establishment request for besteffort, the PDSN 140 transmits a connection establishment response forbest effort to the base station 120 (processing 203). By this, theconnection for best effort is established between the terminal 110 andthe PDSN 140, and the terminal 110 can communicate with the Internetthrough the best effort (processing 204). In this embodiment, as anexample, both a QoS terminal and a non-QoS terminal are first connectedthrough the best effort.

After the connection for best effort is established, the PDSN 140 refersto the QoS information table 141 based on the terminal registrationnumber received in the foregoing processing 202, and acquires a down QoSrequested bandwidth and an up QoS requested bandwidth corresponding tothe terminal registration number. For example, in the case where theconnected terminal 110 is the QoS request terminal, the down and up QoSrequested bandwidths are stored in the QoS information table 141, andthe others are not stored therein. When acquiring the down and up QoSrequested bandwidths, the PDSN 140 transmits a connection establishmentinstruction for QoS to the base station 120 (processing 205). Theconnection establishment instruction for QoS includes the down QoSrequested bandwidth and the up QoS requested bandwidth of the connectedterminal 110. Further, it may include a terminal registration number. Onthe other hand, the down and up QoS requested bandwidths are not storedand can not be acquired, the PDSN 140 terminates the processing. In thiscase, the communication in best effort is continued between the terminal110 and the PDSN 140.

FIG. 7 is a flowchart of the operation of the base station 120 havingreceived the connection establishment instruction for QoS. The basestation 120 having received the connection establishment instruction forQoS stores the value of the down QoS requested bandwidth and the valueof the up QoS requested bandwidth included therein into the requestedbandwidth storage part 510 (processing 701). They may be storedcorrespondingly to, for example, the terminal registration numberreceived in processing 201 or the terminal registration number includedin the connection establishment instruction for QoS. Besides, the basestation 120 obtains the value of A_(i) from the QoS requested bandwidthuniquely, and similarly stores it into the requested bandwidth storagepart 510 (processing 702). Incidentally, the way of obtaining the valueof A_(i) may be a previously determined suitable method such as aconventional method.

The base station 120 calculates, with respect to each of the up and downtransmissions, the wireless resource available rate of the channelthrough which the best effort call of the terminal 110 is provided(processing 703, processing 704). The wireless resource available rateof the channel is obtained from the wireless resource usage rate of 1channel. The wireless resource usage rate of the channel in the downtransmission is calculated by the foregoing expression (2) using thedown QoS requested bandwidth B_(i) of each terminal i stored in therequested bandwidth storage part 510 and the time average R_(i) of thereceivable data rate of each terminal i managed by the receivable datarate reception-management part 550. The wireless resource usage rate inthe up transmission is calculated by expression (3) using the ROTthreshold value T₁ stored in the ROT threshold value storage part 520and the value T of ROT received in the ROT reception-management part570. That is, the wireless resource available rate of the down channelis

$1 - {\sum\limits_{i}\frac{B_{i}}{R_{i}}}$

and the wireless resource available rate of the up channel is

1−T/T₁

where, i denotes all terminals (first terminals) which perform QoScommunication with the base station 120.

Next, the base station 120 calculates the wireless resource usage ratenecessary for the terminal (second terminal) negotiated in processing201 to ensure the QoS requested bandwidth. The wireless resource usagerate of the terminal 110 in the down transmission is calculated by theforegoing expression (1) using the down QoS requested bandwidth B_(i) ofthe terminal 110 stored in the requested bandwidth storage part 510 andthe time average R_(i) of the receivable data rate of the terminal 110managed by the receivable data rate reception-management part 550(processing 705).

Specifically, the base station 120 (for example, the control part 530,the same applies hereinafter) acquires the corresponding down QoSrequested bandwidth B from the requested bandwidth storage part 510based on the terminal registration number received in processing 201 orthe terminal registration number included in the connectionestablishment instruction for QoS received in processing 205.Incidentally, the down QoS requested bandwidth received in processing205 may be used. Besides, the base station 120 acquires thecorresponding data rate R from the receivable data ratereception-management part 550 based on the received terminalregistration number. The base station 120 calculates B/R in accordancewith the acquired values, and obtains the down wireless resource usagerate of the terminal 110 necessary to ensure the down QoS requestedbandwidth B.

Besides, the base station 120 calculates the up wireless resource usagerate of the terminal 110 by multiplying the wireless resource usage rate(T/T₁) of the channel by S/N (P_(i)) of the pilot channel for eachterminal 110 of the S/N reception-management part 560 and A_(i) for eachterminal 110 stored in the requested bandwidth storage part 510(processing 706). That is, the calculation is performed by the foregoingexpression (4).

Specifically, the base station 120 (for example, the control part 530)acquires the corresponding S/N value from the S/N reception-managementpart 560 based on the terminal registration number received inprocessing 201 or the terminal registration number included in theconnection establishment instruction for QoS and received in processing205, and acquires A_(i) corresponding to the foregoing terminalregistration number from the requested bandwidth storage part 510.Besides, the base station 120 acquires the ROT threshold value T₁ storedin the ROT threshold value storage part 520 and the value of ROT, storedin the ROT reception-management part 570, of the channel through whichthe terminal 110 communicates. The base station 120 obtains the upwireless resource usage rate of the terminal 110 by expression (4).

The base station 120 judges whether the wireless resource available rateof the channel is larger than the necessary wireless resource usage ratein both the up and down transmissions (processing 707), and when largerin both the up and down transmissions, the connection establishmentinstruction for QoS is transmitted to the PDSN 140 (processing 708, FIG.6: processing 206). On the other hand, in the up or down transmission,when the wireless resource available rate of the channel is smaller thanthe necessary wireless resource usage rate (processing 707), the basestation 120 does not transmit the connection establishment instructionfor QoS to the PDSN 140, and terminates the processing. At this time,the terminal 110 continues the communication while maintaining the besteffort. The base station 120 may repeat the foregoing processings 703 to708 with respect to another channel. In the case where the necessarywireless resource usage rate is equal to the wireless resource availablerate of the channel, the connection establishment instruction for QoSmay be transmitted, or the processing may be terminated.

Return to FIG. 6, the PDSN 140 having received the connectionestablishment instruction for QoS transmits the connection establishmentresponse for QoS to the base station 120 (processing 207). By this, theconnection for QoS is established between the terminal 110 and the PDSN140 (processing 208).

Incidentally, identifiers which can identify the down transmission, theup transmission and both the transmissions are made to be included inthe connection establishment instruction for QoS, and QoS communicationmay be performed only in one of the up and down transmissions in whichthe wireless resource available rate of the channel is larger than thenecessary wireless resource usage rate. For example, an identifierindicating a direction (up or down) of a channel in which the wirelessresource available rate of the channel is larger, and the connectionestablishment instruction for QoS are transmitted to the PDSN 140, andthe connection for QoS may be established only in the single directioncorresponding to the identifier.

(Modified Example)

When the base station 120 has the QoS information table 141, theconnection establishment instruction for QoS can be transmitted to thePDSN 140 at the stage of processing 202. For example, after thenegotiation of processing 201, the up and down QoS requested bandwidthsare acquired from the QoS information table owned by the base station120, and the QoS provision possible/impossible calculation (processing702 to processing 708) is performed, and when the QoS can be provided,processing 202 to processing 205 are not performed, but the connectionestablishment instruction for QoS is transmitted to the PDSN 140 fromthe first (processing 206). On the other hand, when the QoS can not beprovided, the connection establishment request for best effort can alsobe transmitted to the PDSN 140 as in processing 202.

In this case, since the communication has not been previously performedin best effort, there is no time to calculate the average data rate R.As the wireless resource usage rate which is necessary for the terminal110 to ensure the requested bandwidth and is used in the QoS provisionpossible/impossible calculation, in the down transmission, an averageR_(AVE) of the receivable data rate of all the terminals 110 of thechannel expressed by the following expression may be used in theexpression (1) instead of R_(i).

B_(i)/R_(AVE)  (5)

On the other hand, in the up transmission, the following expression maybe used in which an average P_(AVE) of S/N of pilot signals received inthe base station 120 in the channel and over all the terminals 110 isused instead of P_(i) in the expression (4).

$\begin{matrix}{A_{i} \times P_{AVE} \times \frac{T}{T_{1}}} & (6)\end{matrix}$

Besides, as described before, the connection for QoS in both the up anddown transmissions may be established only in the case where the QoS canbe provided in both the up and down transmissions, or connection for QoSmay be established only in one side when the QoS can be provided only inthe one side. Besides, in the case where the QoS can be provided inneither the up and down transmissions, call connection may be rejected,or a connection establishment request for best effort is transmitted tothe PDSN 140 and the connection for best effort may be established.

2. Second Embodiment

Next, a second embodiment will be described.

For example, the first embodiment relates to the processing at the timeof new connection and the time of connection by handoff, while thesecond embodiment relates to a processing on a connected terminal 110.For example, a following processing is periodically performed.

Since a hardware structure in the second embodiment and the definitionof a wireless resource usage rate are similar to those of the firstembodiment, their description will be omitted.

(Operation)

FIG. 8 is a flowchart in the second embodiment. A base station 120periodically performs respective processings of the flowchart of FIG. 8.First, the flow of the processing will be described in brief.

In both up and down transmissions, the wireless resource usage rate of achannel is calculated using the foregoing expressions (2) and (3)(processing 401). In the case where there is a channel in which thewireless resource usage rate exceeds a first threshold value (forexample, 1) (processing 402), the base station 120 obtains the wirelessresource usage rate of the terminal 110 performing the QoS communicationin the channel by, for example, the expression (1) for the downtransmission and by the expression (4) for the up transmission(processings 403 and 404), and it is checked whether there is a terminalin which the wireless resource usage rate exceeds a second thresholdvalue (for example, 1) (processing 405).

When there is a terminal 110 in which the wireless resource usage rateexceeds 1 (processing 405), since the terminal 110 is in such a statethat the requested bandwidth can not be ensured even if all wirelessresources are allocated, the base station 120 changes the terminal 110in such a state to the best effort communication (processing 406). Forexample, by the change of the wireless environment, there can occur acase where the requested bandwidth can not be ensured according to thetime. The base station 120 repeats the foregoing processings 404 to 406on all terminals 110 in which the QoS communication is performed(processing 407).

In the case where the wireless resource usage rate of the channelexceeds 1 nevertheless (processing 408), the base station 120 confirmswhether another channel exists (processing 409). Here, the anotherchannel is, for example, a channel of another frequency, andinformation, such as ROT of the channel, a QoS requested bandwidth ofthe terminal 110 communicating through the channel, S/N, and a datarate, is managed in the respective blocks of the base station 120.

When the another channel exists, the base station 120 calculates whetheror not, in the case where the terminal 110 is handed off to the anotherchannel in the descending order of magnitude of the wireless resourceusage rate of the terminal 110, the wireless resource usage rates ofboth the handoff source channel (first channel) after the handoff andthe handoff destination channel (second channel) become smaller than 1(processings 412 to 414). At that time, in processing 412, the wirelessresource usage rate of the handoff source after the handoff iscalculated by, for example,

wireless resource usage rate of channel of handoff source beforehandoff−wireless resource usage rate of terminal before handoff.  (7)

As the wireless resource usage rate of the channel of the handoff sourcebefore the handoff, for example, the value obtained in processing 401can be used. As the wireless resource usage rate of the terminal 110before the handoff, for example, the value obtained in processing 404can be used.

Besides, in processing 413, the wireless resource usage rate of thehandoff destination after the handoff is calculated by, for example,

wireless resource usage rate of channel of handoff destination beforehandoff+wireless resource usage rate of terminal after handoff.  (8)

As the wireless resource usage rate of the channel of the handoffdestination before the handoff, for example, with respect to the channelof the handoff destination, values obtained by the foregoing expression(2) and expression (3) can be used. As the wireless resource usage rateof the terminal 110 after the handoff, the expression (5) can be usedfor the down transmission, and the expression (6) can be used for the uptransmission. The detailed processing of processings 412 and 413 will bedescribed later.

As a result of the calculation, in the case where the terminal 110exists in which the wireless resource usage rates of the channels ofboth the handoff source and the handoff destination become smaller than1 by the handoff (processing 414), the base station 120 transmits thehandoff instruction including identification information to identify thechannel of the handoff destination from the handoff instruction part 540to the terminal 110, and hands off the terminal 110 to the channel ofthe handoff destination (processing 415).

The terminal 110 is changed and the processing is repeatedly performeduntil the wireless resource usage rate of the channel becomes 1 or lessor it is found that there is no terminal 110 which can be handed off(processing 411 to processing 418). In the case where a terminal whichcan be handed off disappears while the wireless resource usage rate ofthe channel does not become 1 or less, and in the case where anotherchannel exists, the channel is changed and the processing is repeated(processing 410 to processing 419). Incidentally, in the case where therespective conditions are not satisfied in processings 402, 408 and 409,the processing is terminated. Besides, in processing 417, the processingexits from the repeated processing (processing 410 to processing 419)and is terminated.

In this embodiment, although the first threshold value of the wirelessresource usage rate of the channel, which serves as an opportunity tochange the communication of the terminal 110 to the best effort, is made1, another value may be set as the threshold value. Besides, in thisembodiment, although the second threshold value of the wireless resourceusage rate of the terminal 110, which serves as an opportunity to handoff the terminal 110, is made 1, another value may be set as thethreshold value.

The processing (processing 412 to processing 415 of FIG. 8) to hand offthe terminal 110 to another channel will be described below in detail.Incidentally, although the following description will be made whiledifferentiating between up and down processings for convenience, boththe up and down processings may be performed in parallel, or may beperformed in series. Besides, only the down processing or only the upprocessing may be performed. Besides, in the following description, itis assumed that one or plural terminals (first terminals) performcommunication through a first channel of the base station 120, and otherone or plural terminals (third terminals) perform communication througha second channel.

First, the down processing will be described. At processing 412, first,based on a first down QoS requested bandwidth Bi requested by one orplural first terminals i during QoS communication through the firstchannel, and a first data rate Ri which the first terminal i can receiveand which depends on changing the data amount stored in each time slotaccording to wireless environment, the base station 120 obtains a firstdown wireless resource usage rate in the first channel by the followingexpression.

$\sum\limits_{i}\frac{B_{i}}{R_{i}}$

Here, as the down QoS requested bandwidth and the data rate, valuesstored in the requested bandwidth storage part 510 and the receivabledata rate reception/management part 550 can be used. The same applies toa subsequent processing.

Besides, the base station 120 obtains a second down wireless resourceusage rate of the second terminal, which is necessary to ensure the downQoS requested bandwidth B, by dividing the second down QoS requestedbandwidth B requested by an arbitrary second terminal (for example, oneof the first terminals) during QoS communication through the firstchannel by the second data rate R which the second terminal can receive.

The base station 120 obtains a predicted value of a down wirelessresource usage rate in the first channel after the second terminal ishanded off to the second channel by subtracting the second down wirelessresource usage rate of the second terminal from the obtained first downwireless resource usage rate in the first channel. That is, thepredicted value of the down wireless resource usage rate of the handoffsource (first channel) after the handoff is expressed by the followingexpression.

$\begin{matrix}{{{predicted}\mspace{14mu} {value}} = {{\sum\limits_{i}\frac{B_{i}}{R_{i}}} - \frac{B}{R}}} & \left( 7^{\prime} \right)\end{matrix}$

In processing 413, first, based on a third down QoS requested bandwidthB_(k) requested by one or plural third terminals k during QoScommunication in the second channel, and a third data rate R_(k) whichthe third terminal k can receive and which depends on data amount storedin each time slot and changed according to wireless environment, thebase station 120 obtains a third down wireless resource usage rate inthe second channel by the following expression.

$\sum\limits_{k}\frac{B_{k}}{R_{k}}$

Besides, the base station 120 obtains a fourth down wireless resourceusage rate of the second terminal after the second terminal hands off tothe second channel by dividing the second down QoS requested bandwidth Brequested by the second terminal by the average R_(AVE) of the thirddata rate Rp (B/R_(AVE)) which each terminal 110 communicating throughthe second channel can receive.

The base station 120 obtains a predicted value of a down wirelessresource usage rate in the second channel after the second terminalhands off to the second channel by adding the fourth down wirelessresource usage rate of the second terminal to the third down wirelessresource usage rate in the second channel. That is, the predicted valueof the down wireless resource usage rate of the handoff destination(second channel) after the handoff is

$\begin{matrix}{{{predicted}\mspace{14mu} {value}} = {{\sum\limits_{k}\frac{B_{k}}{R_{k}}} + \frac{B}{R_{AVE}}}} & \left( 8^{\prime} \right)\end{matrix}$

expressed by the following expression.

In the case where both the obtained predicted value of the down wirelessresource usage rate in the first channel and the predicted value of thedown wireless resource usage rate in the second channel respectivelybecome the previously determined threshold values (for example, 1) orless (processing 414), the base station 120 hands off the secondterminal from the first channel to the second channel (processing 415).

Next, the up processing will be described.

In processing 412, first, the base station 120 obtains a first upwireless resource usage rate in the first channel by dividing ROT (RiseOver Thermal) T_(a) of the first channel by a previously determinedfirst threshold value T₁ indicating an allowable upper limit of the ROT(T_(a)/T₁). Here, as the ROT (T_(a)) and the first threshold value T₁,values stored in the ROT reception/management part 570 and the ROTthreshold value storage part 520 can be used.

The base station 120 obtains a second up wireless resource usage rate ofthe second terminal necessary to ensure an up QoS requested bandwidthrequested by an arbitrary second terminal i during QoS communicationthrough the first channel by the following expression:

A×P×T_(a)/T₁

where, A: a ratio of the total transmission power to transmission powerof a pilot channel when the second terminal transmits data in the up QoSrequested bandwidth, which is a value uniquely determined according tothe up QoS requested bandwidth, P: S/N of the pilot channel of thesecond terminal, T_(a): ROT of the first channel, and T₁: previouslydetermined first threshold value indicating the allowable upper limit ofROT.

The base station 120 obtains a predicted value of the up wirelessresource usage rate in the first channel after the second terminal handsoff to the second channel by subtracting the second up wireless resourceusage rate of the second terminal from the first up wireless resourceusage rate in the first channel. That is, the predicted value of the upwireless resource usage rate of the handoff source (first channel) afterthe handoff is expressed by the following expression:

predicted value=T _(a) /T ₁ −A×P×T _(a) /T ₁.  (7″)

Next, the base station 120 obtains a third up wireless resource usagerate in the second channel by dividing ROT (T_(b)) of the second channelby a previously determined second threshold value T₂ indicating anallowable upper limit of the ROT (T_(b)/T₂).

The base station 120 obtains a fourth up wireless resource usage rate ofthe second terminal after the second terminal hands off to the secondchannel by the following expression:

A×P_(AVE)×T_(b)/T₂

where, A: a ratio of the total transmission power to transmission powerof the pilot channel when the second terminal transmits data in the upQoS requested bandwidth, which is a value uniquely determined accordingto the up QoS requested bandwidth, P_(AVE): an average of S/N of thepilot channel of all the terminals 110 communicating through the secondchannel, T_(b): ROT of the second channel, and T₂: a previouslydetermined second threshold value indicating an allowable upper limit ofROT.

The base station 120 obtains a predicted value of the up wirelessresource usage rate in the second channel after the second terminalhands off to the second channel by adding the fourth up wirelessresource usage rate of the second terminal to the third up wirelessresource usage rate in the second channel. That is, the predicted valueof the up wireless resource usage rate of the handoff destination(second channel) after the handoff is expressed by the followingexpression:

predicted value=T _(b) /T ₂ +A×P _(AVE) ×T _(b) /T ₂  (8″)

In the case where both the obtained predicted value of the up wirelessresource usage rate in the first channel and the predicted value of theup wireless resource usage rate in the second channel respectivelybecome the previously determined threshold values (for example, 1) orless, the base station 120 hands off the second terminal from the firstchannel to the second channel.

Incidentally, the first embodiment and the second embodiment arecombined, and for example, after the communication is started in thefirst embodiment, the second embodiment may be performed.

Incidentally, in this embodiment, although the description has beengiven to the case where the down transmission is the TDMA, the inventioncan be applied also to the case where the up transmission is the TDMA.Besides, although the description has been given to the case where theup transmission is the CDMA, the invention can be applied also to thecase where the down transmission is the CDMA.

The invention can be used for the industry relating to the communicationsystem to provide QoS, and the communication service.

1. A base station in a wireless communication system comprising: a basestation having a first and a second channels and communicating with aterminal by wireless and by time division multiplexing, and a node toperform best effort communication and QoS communication with theterminal, wherein the base station obtains a first wireless resourceusage rate in the first channel, based on a first requested bandwidthB_(i) requested by one or plurality of first terminals i during QoScommunication through the first channel and a first data rate R_(i)which the first terminal i can receive and which depends on changing adata amount stored in each time slot according to wireless environment,by a following expression: $\sum\limits_{i}\frac{B_{i}}{R_{i}}$ whereinthe base station obtains a second wireless resource usage rate of thesecond terminal, which is necessary to ensure a requested bandwidth B,by dividing the second requested bandwidth B requested by an arbitrarysecond terminal during QoS communication through the first channel by asecond data rate R which the second terminal can receive, wherein thebase station obtains a predicted value of a wireless resource usage ratein the first channel after the second terminal hands off to the secondchannel by subtracting the second wireless resource usage rate of thesecond terminal from the first wireless resource usage rate in the firstchannel, wherein the base station obtains a third wireless resourceusage rate in the second channel, based on a third requested bandwidthB_(k) requested by one or plurality of third terminals k during QoScommunication through the second channel and a third data rate R_(k)which the third terminal k can receive, which depends on changing a dataamount stored in each time slot according to wireless environment, by afollowing expression: $\sum\limits_{k}\frac{B_{k}}{R_{k}}$ wherein thebase station obtains a fourth wireless resource usage rate of the secondterminal after the second terminal hands off to the second channel, bydividing the second requested bandwidth B requested by the secondterminal by an average R_(AVE) of the data rate which each terminalcommunicating through the second channel can receive, wherein the basestation obtains a predicted value of a wireless resource usage rate inthe second channel after the second terminal hands off to the secondchannel by adding the fourth wireless resource usage rate in the secondterminal to the third wireless resource usage rate in the secondchannel, and wherein the base station hands off the second terminal fromthe first channel to the second channel in a case where both theobtained predicted value of the wireless resource usage rate in thefirst channel and the predicted value of the wireless resource usagerate in the second channel respectively become equal to or less thanpreviously determined threshold values.
 2. The base station according toclaim 1, wherein in a case where the obtained second wireless resourceusage rate of the second terminal is larger than the previouslydetermined second threshold value, the base station changes the secondterminal from the QoS communication to the best effort communication. 3.The base station according to claim 1, further comprising: a requestedbandwidth storage part in which a first requested bandwidth requested byone or plurality of first terminals during QoS communication and asecond requested bandwidth requested by the second terminal trying toperform QoS communication are stored for each terminal; a data ratereception management part that receives a data amount which the firstand the second terminals can receive in each time slot from theterminals, which depends on changing the data amount stored in each timeslot according to wireless environment, calculates a first and a seconddata rates which the first and the second terminals can receive byobtaining a time average value of the data amount for each terminal, andstores the data rates for each terminal; and a control part to controlthe base station.